(1) Field of the Invention
The present invention relates to a bus control system having a plurality of processors respectively including inter-multiprocessor controllers (hereinafter also referred to as IPCs) connected to a communication bus, for controlling inter-multiprocessor communication by polling from an inter-multiprocessor bus controller.
In recent years, data processing systems have been used which have a plurality of processors connected to each other by a communication bus and carrying out different proceedings so that necessary data are transferred through the bus and received for common use.
When such a communication among a plurality of processors is to be carried out, a system is known in which the respective processors are sequentially interrogated by polling to determine whether or not a bus-use requirement is present.
(2) Description of the Related Art
In a conventional art, the communication bus is occupied by one IPC of a talker during a period from the issuance of the allowance signal to use the communication bus to the generation of the completetion notification of the data transfer from the IPC of the talker, and the occupation period includes data transfer from an IPC in a listener to a main memory in the listener by a direct memory access control. The data transfer within the listener, however, does not need to use the communication bus between the talker and the listener but only needs the data bus within the listener. Therefore, the period of occupying the communication bus in the conventional art is too long and the efficiency in using the communication bus is bad. The communication bus is commonly used by a number of processors. Therefore, if the period occupied for one time of use of the bus is too long, a negative influence is had on the processing ability of the multi-processor system. In particular, along with developments in the processing speed of processors, there is a problem in that the processing ability of the total system is deteriorated if the time for data transfer between processors is too long.